Nonelectrode rf light source

ABSTRACT

A nonelectrode RF light source of directional radiation which is an optically transparent bulb filled with a discharge gas, holding a starting inductor having turns of a monotonically decreasing diameter. For its whole length and shape, the inductor is enclosed in an insulating tube whose inner surface has a coating acting as an optical reflector. The said light source produces a discharge with luminous and spectral characteristics constant with time and uniform in spatial distribution.

United States Patent Gruzdev et al.

[451 Jan. 18, 1972 [54] NONELECTRODE RF LIGHT SOURCE [72] inventors:Valentin Anatolievich Gruzdev, korpus 338 B, kv. 37; Boris VasilievichSkvortsov, korpus 308, kv. 25; Nikolai Vasilievich Propkopenko, korpus445, kv. 215; Evgeny Alexandrovich Nedzvetsky, korpus 329, kv. 69, allof Zelenograd Moskovskoi Oblasti, U.S.S.R.

[22] Filed: Feb. 12,1970

[2]] Appl.No.: 10,721

[52] US. Cl ..313/31, 313/36 [5 1] Int. Cl. [58] Field of Search [5 6]References Cited UNITED STATES PATENTS 2,030,957 2/1936 Bethenod et al..3l5/248 2,728,029 12/1955 Finger ..3l3/3l Primary Examiner-William L.Sikes Assistant Examiner-Conrad Clark Attorney-Waters, Roditi, Schwartz& Nissen ABSTRACT A nonelectrode RF light source of directionalradiation which is an optically transparent bulb filled with a dischargegas, holding a starting inductor having turns of a monotonicallydecreasing diameter. For its whole length and shape, the inductor isenclosed in an insulating tube whose inner surface has a coating actingas an optical reflector.

The said light source produces a discharge with luminous and spectralcharacteristics constant with time and uniform in spatial distribution.

2 Claims, 1 Drawing Figure PATENTED JAN 1 8 r972 llllllllarlrNONELECTRODE RF LIGHT SOURCE The present invention relates togas-discharge devices, and more specifically to nonelectrode RF lightsources intended for use as, for example, sunlamps.

There exists a nonelectrode RF light source comprising an opticallytransparent glass bulb filled with a discharge gas, and a startinginductor placed inside the bulb and made in the fonn of a solenoidenergized by an RF oscillator.

The starting inductor is fabricated from a copper wire wound into athree-demensional helix enclosed for its whole length and shape in atransparent insulating tube through which a cooling agent is passed toabstract the heat from the inductor.

The said nonelectrode light source has a low coefficient of utilizationof the discharge radiation, which is especially noticeable when thenonelectrode RF light source is used in optical devices of directionalradiation.

Besides, the passage of some radiation through the cooling agentproduces a spatial inhomogeneity in the energy spectrum of the dischargeradiation.

A particular object of the invention is to provide a nonelectrode RFlight source which emits directional radiation and secures a highcoefficient of utilization of radiation along with a uniform energyspectrum of the discharge radiation.

The present invention resides in a nonelectrode RF light sourcecomprising a bulb made from an optically transparent material and filledwith a discharge gas, which holds a starting inductor in the fonn of asolenoid enclosed for its whole length and shape in an opticallytransparent insulating tube, the inner surface of the insulating tubehas, according to the invention, a coating which acts as an opticalreflector, while the inductor has turns of a monotonically decreasingdiameter.

It is preferable to make the said coating from an electricallyconducting material, such as silver. In such a case, the coating willalso act as a starting inductor.

The nonelectrode light source disclosed herein is a source ofdirectional radiation and produces a discharge with luminous andspectral characteristics constant with time and uniform in spatialdistribution.

The invention will be best understood from the following description ofa preferred embodiment when read in connection with the drawing, whichsows a cross-sectional view through a nonelectrode RF light sourceaccording to the invention.

Referring to the drawing, there is a nonelectrode RF light sourcecomprising a quartz bulb l with two pipe unions 2, filled a dischargegas, such as xenon, under a pressure of 250 to 300 mm. Hg.

The bulb 1 holds a quartz insulating tube 3 which is a threedimensionalhelix with turns of a monotonically decreasing diameter such that theinside surface 4 of the helix has the shape of a cup.

The inner surface of the insulating tube 3 has a coating 5 of anelectrically conducting material with a high reflection coefficient foroptical radiation, such as'silver. The coating 5 acts as both an opticalreflector and a starting inductor. Inside the insulating tube 3 there isa duct 6 to let in a cooling agent, such as water. The ends of theinsulating tube 3 are led out of the bulb 1 through the pipe unions 2which are sealed to metal adapters 7 intended for connection of thelight source to an RF oscillator and a cooling system.

The light source disclosed herein operates as follows.

When the light source is connected to an RF oscillator (not shown in thedrawing), an RF current is caused to flow in the starting inductor (thecoating 5).

The alternating electromagnetic field established in the bulb 1 leads tothe ionization of the discharge gas within the space bounded by thecup-shaped surface 4, resulting in a discharge which gives out aluminous flux. The emitted luminous flux is shaped within the solidangle bounded by the surface 4 and is a sum of the luminous flux due tothe direct radiation of the plasma within the said solid angle and theluminous flux reflected from the mirror walls of the surface 4.

Among the advantages of the invention disclosed herein IS that theemitted luminous flux has an increased density (two or three times asgreat as compared with the nonelectrode light source in which thestarting inductor has the shape of a cylindrical three-dimensionalhelix).

It should also be noted that an inductor with turns of a variablediameter secures a steady discharge.

Besides, since the luminous flux in the light source disclosed herein isdirectional and is not radiated through the walls of the insulating tube3, but is reflected from them, it is not affected by variations in thetransparency of the quartz insulating tube 3 that may be caused by, say,insignificant impurities in the cooling water.

The cooling agent used in the light source disclosed herein may becommon (nondistilled) water, in which case the source still secures aconstant intensity of the luminous flux, its spectral composition, andthe radiation pattern. Because of these advantages, the nonelectrode RFlight source disclosed herein may be used in spectroscopy, colorcontrol, and in tests for color fastness.

What is claimed is:

l. A nonelectrode RF light source comprising: a bulb made from anoptically transparent material and filled with a discharge gas; astarting inductor made in the form of a solenoid with turns of amonotonically decreasing diameter and enclosed in said bulb; aninsulating tube from an optically transparent material enclosing saidinductor for its whole length and shape; a coating applied to the innersurface of said insulating tube and acting as an optical reflector.

2. A light source, as claimed in claim 1, in which said coating is madefrom an electrically conducting material.

1. A nonelectrode RF light source comprising: a bulb made from anoptically transparent material and filled with a discharge gas; astarting inductor made in the form of a solenoid with turns of amonotonically decreasing diameter and enclosed in said bulb; aninsulating tube from an optically transparent material enclosing saidinductor for its whole length and shape; a coating applied to the innersurface of said insulating tube and acting as an optical reflector.
 2. Alight source, as claimed in claim 1, in which said coating is made froman electrically conducting material.